1. Field of the Invention
The present invention relates to a positioning and fixing apparatus for positioning a movable member such as a switch girder for a linear motor car of the levitation type in a predetermined position and fixing it thereat.
2. Background of the Invention
An apparatus for positioning a girder of a linear motor car of the levitation type in a predetermined position at which it is switched and holding it thereat, as shown in FIGS. 6 and 7, comprises centering means 102 fixed to a movable member 101 i.e., a switch girder and a roller 105 provided on a swing arm 104 pivoted in a vertical plane by a stationary base 103. When the movable member 101, movable linearly or swingeable by means of wheels 107 guided by rails 106, approaches in the vicinity of the predetermined position and is then stopped thereat, the swing arm 104 is swung down by an oil cylinder 108. The centering means 102 is formed, as shown in FIG. 7, of a guide member comprising a groove 109 fittingly receiving a roller 105 which serves as a fixing means provided on the swing arm 104, and a chute shaped guide groove 110 guides the roller 105 into the groove 109. Upon swinging down of the swing arm 104, the roller 105 enters into the groove 109 through the guide groove 110 and the movable member 101 is centered and fixed thereat.
In the conventional centering means described above, the roller 105 which serves as the fixing means is forcibly pushed into the groove 109 of the centering means 102. Therefore, there is a problem that abrasion between the roller 105 and the wall material of the groove 109 may occur. Once such abrasion occurs, a precise centering operation becomes impossible and repair thereof is very difficult. In view of this, an extra centering means is always required so that it can be exchanged depending upon the degree of abrasion. This means an increased cost.